Answer / hiren

Parallel connection to Voltage source

Answer / carl_ellis

A second power supply is wired in parallel with the first, but redundant/parallel power supplies should be decoupled from each other with power diodes, where each diode is forward biased on the power supply (+) output with the diode (-) coupled in common to the load).

The diodes need to be rated to carry the full current load. If diodes are not used, a severe fault in one of the power supplies could cripple the output of the 2nd power supply.

The isolation diodes must be installed on a heatsink to maintain operating temperature at a safe level. The power dissipation on the diode is determined by the product of the current passing through the diode and its "on" diode voltage drop.

Some recommend the use of Schottky diodes rather than silicon diodes becaus Schottky diode has a lower voltage drop so it runs cooler.

There are commercial diode decoupling/isolation packages sold with appropriately sized heat sinks to keep the diodes within temperature spec.

Carl Ellis
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